Open Letter to all PCP airgun manufacturers: The need for standardization

Started by Alan, November 18, 2020, 03:03:33 PM

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Alan

The firearms industry's SAAMI (Sporting Ammunition & Arms Manufacturing Institute), establishes, and records, the requisite standards for the various powder cartridges available to the public. These standards are important to assure safe operation of all sporting arms, regardless of who makes or sells either the ammunition or the arms to fire them.

On the other hand, the airgun industry doesn't have a standards committee, albeit there is an assumed standard for caliber diameters. For pellets (except for caliber .177), the land diameter is used (e.g.: .220, 250, .300 etc.). For slugs, they tend to follow the SAAMI dimensions for the bore diameter (.224, 257, 308, etc.). Heretofore, this has served the airgun industry very well.

In the last 25 years or so, PCP  (Pre-Changed Pneumatic) airguns have become very popular. In fact, they've taken the airgun hobby by storm. Just about any attribute you might want in a PCP airgun, is readily available on the open market. The number of manufacturers has also increased, as has the power and capabilities, some rivaling the firearms industry's offerings. Unfortunately, they haven't followed suit with respect to the myriad of PCP airgun refilling apparatus. And... That is the subject of this open letter.

Regulars here, will certainly know about the issues surrounding the use of so-called Foster Fittings, used in the recharging (refilling with air) of the majority of marketed PCP airguns. Here is the thread: (https://airgunguild.com/airgun-tanks-compressors-and-filling/foster-parker-air-venturi-and-various-chinese-fittings)

There are several issues (some hidden) which need to be addressed. The most important one is, cross pollination. That is to say, that one manufacture's fitting, will fit onto, or into, another manufacture's fitting. Seems reasonable, but that isn't the case! For example, between Steve Dampier (our illustrious webmaster), and yours truly (co-owner of airgunguild.com), we've measured the male fitting's outside diameter from .3079" to as large as .3088", and female fitting's inside diameter from .3098" to .3168"! (From metric, divide the mm by 25.4 to get the decimal size.)

It should be obvious from the measurements, that cross pollination is iffy at best, between the various fittings, depending on who made them. In fact, a large variation (several ten thousands of an inch) can be seen between batches of so-called Foster Fittings from one given manufacturer!

After spending a few hours looking, it appears there is no US patent, on the so-called Foster Fittings most of us use. It is almost as if we're dealing with a de facto-standard (e.g.: in fact, or in effect, whether by right or not)!

Not wanting to belabor the issue, there is another potentially dangerous aspect of these mis-matings: Security!

Depending on the manufacturer, the female Foster Fitting (used for lack of the correct term), use what is commonly referred to as a ball lock. Some have just 4 balls, some 5, and the best ones, 6. Quite obviously, the more balls in the lock, the less the pressure exerted on each ball, and its subsequent mating surface. Remember, we're typically filling to a max of 4,500 PSI (310 BAR). Should one of the female or male parts of the fitting fail for whatever reason, the results could be life-threatening!

It is, in my opinion, that the various manufactures of PCP airguns, should establish some sort of industry standards committee to address this all-important issue for both safety, and compatibility.

Alan Applegate
Co-owner, airgunguild.com



Alan

I have a Hill EC-3000 compressor. If you're a fellow Guild member, and you pass through Roswell, NM, I'll fill your tank as a courtesy (4,250 PSI limit).

steveoh

I tell you what, this lack of standardization annoys me to no end.

You have the variety of threaded ends, both male and female for quick releases. Those ends can be:

Metric tapered or straight
British tapered or straight
USA tapered or straight

They are a pain in the neck!


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Smoke4320

I concur. We have both paintball fields, proshop and real gunshop plus moving into PCP airguns as both my hobby and business
Annoying trying to match thread patterns is the least of it.  Potentially dangerous is more likely.
and dont even get me started with the customers who want to make a fill station with galvanized pipe fittings

Alan

Or just as bad, standard old brass fittings.

I think part of the problem, is finding the correct fitting. I've been looking for an adapter from male 5/8X18 to female 7/8X14. The company who used to make these, stopped making them. There is a brass equivalent, but I don't want to even think about brass at 4,500 PSI!
Alan

I have a Hill EC-3000 compressor. If you're a fellow Guild member, and you pass through Roswell, NM, I'll fill your tank as a courtesy (4,250 PSI limit).

flwing

Can you imagine if tire manufacturers were never able to agree on the Schrader valve as a standard for virtually all vehicles in the world?

Come on, air gun producers - pick the Foster Fitting as a standard and save us the hassle of having to buy adapters JUST for your model!

steveoh

Looks like BB stepped up. I'd like to see a ground swell of support from manufacturers to standardize the so-called "Foster Fitting."

https://www.pyramydair.com/blog/2021/06/airgun-standards/

QuoteToday I write about a subject that plagues us all — standards. There are so many that it seems as if there are none.

Foster fitting

At the beginning of this month I lamented that the Foster fitting on the first Seneca Eagle Claw rifle I tested was super-hard to attach to. I had no idea that Foster fittings came in many different sizes. Read this Airgun Wire article by Tom McHale to learn more.

I always wondered why some Fosters were hard to attach to — now I know. But the knowing may not help that much!
Fill probes

I once had an airgun maker tell me their airguns were made to accept a "standard 8 mm fill probe". Great! Except for one or two things. First, how long is the probe for their guns? Will someone else's short probe even put the air release holes far enough into your fill port to get air into the gun?

Also, where are the air release holes located on the probe? Are they somewhere that the air they release has a chance to enter the air intake port on the gun being filled? Or are they out so far that they are on the outside of the gun's fill port?

I criticize Air Arms for their odd-looking fill adaptor, but given that Foster fittings aren't all the same I guess it doesn't make any difference.

Standards that work

Okay, what about standards that do work? Still talking about high pressure air, scuba tanks have a couple standards that are fairly universal. In my limited experience, DIN 200 bar and DIN 300 bar fittings are the same, except for their lengths and the pressures they are designed for. DIN stands for Deutsches Institut für Normung (German Institute for Standardization).The hole in the 300 bar fitting is deeper than the hole in the 200 bar fitting, but the diameter and threads are the same.
Quackenbush .58 Outlaw
Shooting Chairs
Vallejo Ferry Schedule
DAQ .458 LA Outlaw Rifle
DAQ .58 LA Outlaw Rifle
FX Streamline .25
FX M3 Impact 700mm Sniper .25
Benjamin Bulldog .357
QB-79 .177
Crosman 1322
Crosman 1377 - HoRodded 10 FPE
Diana Model 27 (childhood airgun)
Tolman Skiff
Airgun Calculator

steveoh

And another article by Tom McHale of the Airgun Wire. And look here who's quoted!

https://airgunwire.com/airgun-standards-and-non-exploding-coffee-makers/

QuoteA couple of weeks ago I poked some fun at airgun probes and their inherent finickiness, at least for me. Shortly after, I had the pleasure of virtually meeting a couple of gentlemen who wrote in from The Airgun Guild. Self-described as "a friendly place to share one's interest in all things airguns," it's a forum where people like us can share, discuss, pontificate, and solve our collective problems. This is one of the good things about the modern internet: it allows you to make interesting acquaintances like this. Nice to meet you guys!

Anyway, Alan Applegate and Stephen Dampier were kind enough to share some of their ongoing discussion on our collective opportunity to get a bit better on industry standardization. Alan admitted to agreeing with my mild frustration with probes but pointed out additional challenges in the Foster fitting world. "While I share your dislike for probes (mostly based on too many standards), so-called Foster fittings are a mess too. And, for the exact same reason — no defined size standard!"
Quackenbush .58 Outlaw
Shooting Chairs
Vallejo Ferry Schedule
DAQ .458 LA Outlaw Rifle
DAQ .58 LA Outlaw Rifle
FX Streamline .25
FX M3 Impact 700mm Sniper .25
Benjamin Bulldog .357
QB-79 .177
Crosman 1322
Crosman 1377 - HoRodded 10 FPE
Diana Model 27 (childhood airgun)
Tolman Skiff
Airgun Calculator